Semiconductor image sensors are operated to sense light. Typically, the semiconductor image sensors include complementary metal-oxide-semiconductor (CMOS) image sensors (CIS) and charge-coupled device (CCD) sensors, which are widely used in various applications such as digital still camera (DSC), mobile phone camera, digital video (DV), digital video recorder (DVR), optical sensor (proximity sensor, ambient light sensor heart rate sensor, and optical sensing element (optical transceiver) applications. These semiconductor image sensors utilize single or an array of image/optical signal sensor elements, each image/optical signal sensor element including a photodiode and other elements, to absorb light and convert the sensed light into digital data or electrical signals. Thus, it is important for semiconductor image sensors to be able to have good light absorption abilities.